Wednesday, April 26, 2017

Chesapeake Oysters Reveal Long Standing Water Quality Problems

Studying oyster shells dating back to 1250 BC, researchers found a dramatic increase in nitrogen content that began in the early 1800s and increased almost exponentially until present day. That timeline corresponds what is known about human activities in the Chesapeake Bay region at that time: dramatic increases in population, agriculture and forest clearing. While American Indians altered their environment and contributed to higher nitrogen levels in the water, the effects were local. Beginning in the 17th century, an influx of European colonizers led to an increase in agriculture and forest clearing— but it wasn’t until the 19th century that human effects began to dramatically alter nitrogen levels in oysters.

Industrialization and population increases in the 1800s left their mark on the Chesapeake Bay. Between 1830 and 1880, the area’s population tripled. As a result, over 80 percent of forests surrounding the Bay were cleared for farming and development. Plowing and erosion increased the amount of sewage and sediment entering the water, increasing nitrogen levels in the water as well. Oyster populations also declined, thus limiting the ability of the Bay to filter out this influx of pollution.

That was the period when, having mined out the oysters of Long Island Sound and the surrounding areas, the fishermen moved to Chesapeake Bay to continue their rape and pillage.